When do concatenation string, avoid uniting with large size string. It can obstructing code execution that really can display more faster.

Code:
//large string concatenation
$title = ‘title’;
$body = ‘…a very large block…’;
echo “Subject: $title\n\n$body”;

//avoid large string concatenation
$title = ‘title’;
$body = ‘…a very large block…’;
echo “Subject: $title\n\n”;
echo $body;